Ocular hydration sensor

Abstract

Apparatuses, methods, and systems for an ocular hydration sensor/reflectometer system in a near-eye display device are described. In one aspect, a near-eye display device may include a projector to project light onto a user's eye, a photodetector to receive reflections from the tear film of the user's eye (e.g., the tear glints), and a controller to make ocular hydration measurements from the received reflections. The ocular hydration measurements may be used to (1) re-calibrate an eye tracking system of the near-eye display device (by changing parameters such as, e.g., light intensity and/or exposure time); (2) prompt the user to take remedial action; and/or (3) keep track of the user's eye health over time. The projector, photodetector, and/or controller may be integrated into, separate from, or partially integrated/partially separate from the eye tracking system. Collective die-on-wafer processing, embedded motheye lens structures, and adaptive thermal management using thermoelectric coolers are also described.

The invention claimed is: 
     
       1. A near-eye display device, comprising:
 a frame; 
 a projector disposed in the frame to project light onto an eye; 
 a photodetector disposed in the frame to receive a reflection from a tear film of the eye of the light projected onto the eye by the projector; 
 a processor and a non-transitory computer-readable storage medium having an executable stored thereon, which when executed instructs the processor to perform one or more reflectometric measurements of ocular hydration of the eye using the received reflection as input from the photodetector; and 
 an eye tracking system to re-calibrate eye tracking parameters based on the one or more reflectometric measurements, 
 wherein the eye tracking parameters comprise at least one of an intensity of an eye tracking illumination source or an exposure time of an eye tracking photosensor. 
 
     
     
       2. The near-eye display device of  claim 1 , wherein the eye tracking system comprises the projector. 
     
     
       3. The near-eye display device of  claim 1 , wherein the eye tracking system comprises the photodetector. 
     
     
       4. The near-eye display device of  claim 1 , wherein the eye tracking system comprises the processor. 
     
     
       5. The near-eye display device of  claim 1 , wherein the photodetector comprises a polarization sensitive photodetector to de-couple specular reflections from the tear film of the eye and diffuse reflections from a sub-surface of the eye to separate out measurements of the tear film and measurements of the sub-surface of the eye. 
     
     
       6. The near-eye display device of  claim 1 , wherein the projector comprises a projector to project at least one of an augmented reality (AR) or a virtual reality (VR) image. 
     
     
       7. The near-eye display device of  claim 1 , wherein the projector comprises a laser scanning source to project images on a retina of the eye. 
     
     
       8. The near-eye display device of  claim 1 , wherein the projector is integrated into at least one of an augmented reality (AR) image display projector or a virtual reality (VR) image display projector. 
     
     
       9. The near-eye display device of  claim 1 , wherein the projector comprises one or more diffuse light sources. 
     
     
       10. The near-eye display device of  claim 1 , wherein the projector is further to project at least one of polarized light or unpolarized light onto the eye. 
     
     
       11. A method for a near-eye display device, comprising:
 receiving light reflected from a tear film of an eye; 
 measuring ocular hydration using the received light reflected from the tear film; and 
 re-calibrating eye tracking parameters of an eye tracking system of the near-eye display device based on the measuring, 
 wherein the eye tracking parameters comprise at least one of an intensity of an eye tracking illumination source or an exposure time of an eye tracking photosensor. 
 
     
     
       12. The method of  claim 11 , further comprising:
 projecting light to be reflected from the tear film of the eye. 
 
     
     
       13. The method of  claim 11 , wherein the measuring ocular hydration comprises:
 measuring glints from the tear film of the eye. 
 
     
     
       14. The method of  claim 11 , wherein the receiving light reflected from the tear film of the eye comprises:
 de-coupling specular reflections from the tear film of the eye and diffuse reflections from a sub-surface of the eye to separate out measurements of the tear film and measurements of the sub-surface of the eye. 
 
     
     
       15. The method of  claim 14 , further comprising:
 projecting at least one of polarized light or unpolarized light to be reflected from the tear film of the eye, 
 wherein the de-coupling specular reflections from the tear film of the eye and diffuse reflections from a sub-surface of the eye is based on a polarization state of the specular reflections and the diffuse reflections. 
 
     
     
       16. The method of  claim 11 , further comprising:
 determining, using the measuring, whether to prompt a user to take remedial action concerning the eye. 
 
     
     
       17. A method for a near-eye display device, comprising:
 receiving light reflected from a tear film of an eye; 
 determining whether the eye is open and stationary for a sufficient length of time for measuring ocular hydration using the received reflected light; 
 measuring ocular hydration using the received light reflected from the tear film; and 
 re-calibrating eye tracking parameters of an eye tracking system of the near-eye display device based on the measuring. 
 
     
     
       18. The method of  claim 17 , further comprising:
 determining, using the measuring, whether to prompt a user to take remedial action concerning hydration of the eye. 
 
     
     
       19. The method of  claim 18 , wherein the determining comprises:
 determining, using the measuring and input from one or more sensors on the near-eye display device, whether to prompt the user to take remedial action concerning hydration of the eye. 
 
     
     
       20. The method of  claim 17 , further comprising:
 projecting at least one of polarized light or unpolarized light to be reflected from the tear film of the eye, 
 wherein the receiving light reflected from the tear film of the eye comprises de-coupling specular reflections from the tear film of the eye and diffuse reflections from a sub-surface of the eye to separate out measurements of the tear film and measurements of the sub-surface of the eye, and 
 wherein the de-coupling specular reflections from the tear film of the eye and diffuse reflections from the sub-surface of the eye is based on a polarization state of the specular reflections and the diffuse reflections.